It's been proven that people who obsessively worry about some things are far more likely than the general population to have acute problems with those things.
Stress, fear, worry, and a gloom-n-doom attitude have probably killed as many people throughout history as any specific, ie 'quantifiable' disease. Not to make light of
any human disease condition, but sometimes the
a priori fear is more debilitating in the greater sense. The prehistoric caveman who was so terrified of the wooly mammoth that he wouldn't leave his cave to hunt for his food likely died of starvation.
Disclaimer: My doctoral studies were in Architecture rather than Medicine.